Unless VOC are a concern at all, I'd say either hardwood or tile are ok.
-Can be comfortable and warm if used in conjunction with radiant floor heating
-Can be an extremely tough surface (ceramic tile has extremely good scratch resistance)
-Easy to clean
-Can trap a miniscule amount of dust in the grout grooves
-If not used with some form of integrated heating it will buffer temperature changes. There certainly is the option of using a membrane underlayment (ie. Sculer-Ditra) but that will not change the fact that during the colder months the entire tile floor will likely be at a lower temperature than your feet will enjoy. This can be overlooked if the use of slippers during those cooler months is not an issue. It will feel nice in the summer months, assuming you don't live in a dessert (where it get's very cool at night).
-Additional weight: Compared to wood tile weighs a ton, you should have the structure holding up the bedroom assessed by an engineer(not the tile floor sales guy), its not unheard of for a floor to bow as a result of excessive static weight.
If VOC sensitivity is not an issue, I'd recommend a search of the VOC off-gassing difference between other wood flooring options (including laminates, engineered, and hardwood). Once a hardwood floor has been properly finished the only things that might be released are gaseous VOC.
Although its a bit of an assumption, I'd probably first point to all the fabrics found in bedrooms.